Field installed low ambient damper for outdoor rooftop condenser installation

ABSTRACT

A temperature responsive, adjustable louver damper box overlies the hot air discharge opening in the top of a standard rectangular condenser housing exposed to outside air with the forward portion of the box overhanging the front of the condenser housing. Louvers in closed position recirculate at least a part of the hot condenser discharge air through the box for discharge in front of the intake opening of the condenser housing.

iliiited States Patent CONDENSER INSTALLATION [75] Inventor: Richard J.Swartwout, Penn Laird,

[73] Assignee: Dunham-Bush, Incorporated,

Harrisonburg, Va.

[22] Filed: Aug. 28, 1972 [21] Appl. No.: 284,001

[52] US. Cl. 62/183, 62/507 [51] llnt. Cl. F251 39/04 [58] Field ofSearch 62/183, 507

[56] References Cited UNlTED STATES PATENTS 3,004,402 10/1961 Dart62/183 Swartvvout Nov. 6, 1973 FIELD INSTALLED LOW AMBIENT 3,466,8899/1969 Fristoe 4. 62/507 DAMPER FOR OUTDOOR ROOFTOP 3,584,466 6/1971Kaufman et a]. 62/183 Primary Examiner-Meyer Perlin Att0rney-Richard C.Sughrue et al.

[57] ABSTRACT A temperature responsive, adjustable louver damper boxoverlies the hot air discharge opening in the top of a standardrectangular condenser housing exposed to outside air with the forwardportion of the box overhanging the front of the condenser housing.Louvers in closed position recirculate at least a part of the hotcondenser discharge air through the box for discharge in front of theintake opening of the condenser housing.

7 Claims, 3 Drawing Figures FIELD INSTALLED LOW AMBIENT DAMPER FOROUTDOOR ROOF TOP CONDENSER INSTALLATION BACKGROUND OF THE INVENTION 1.Field of the Invention This invention relates to refrigeration systems,and more particularly to an arrangement for controlling the refrigeranthead pressure at low ambient temperatures in a system where thecondenser is normally exposed to the outside air.

2. Description of the Prior Art Condenser coils forming portions ofrelatively large refrigeration systems are conventionally contained byrelatively large rectangular housings mounted on a rooftop or in otherpositions of normal exposure to outside air. Such housings are providedwith an intake opening within the housing permitting entry of relativelycool ambient air for passage over the condenser coil and for dischargethrough a related opening downstream of the condenser, under forced airflow created by electric motor powered-blowers or the like.

In order to maintain the temperature of the air flowing across thecondenser coil within a predetermined range or above a predeterminedmimimum and in order to obtain maximum efficiency in operation of therefrigeration circuit, it is conventional to employ internally of thehousing, sets of damper blades or louvers in order to recirculate someof the already heated air through the condenser by mixing it with theincoming ambient, at times when the ambient temperature is relativelylow. Such recirculation systems as set forth in U. S. Pat. No.3,148,514, are characterized by a plurality of sets of louvers withmultiple temperature controls associated therewith to the control ofpositions of the various louver blades.

In the space conditioning field, particularly in large industrial andcommercial buildings requiring air con ditioning or commercialrefrigeration, a unit conditioner, in terms of the equipment positionedexterior of the building and exposed to the outside air, is constitutedby a rectangular condenser housing in which a vertical sidewall carriesa large opening which acts as the cooling air inlet to the condenser,while a second opening is provided within the'top of and downstream ofthe condenser coil and the blower which permits the heated air, assistedby convection, to escape upwardly and away from the unit.

It is, therefore, a principal object of this invention to provide atleast one assembly constituted by a single set of louver blades whichmay be readily coupled to an existing conventional condenser housing ofthis type providing a low cost, simplified means for regulatingrecirculation of heated condenser discharge air past the condenser coil,so that air temperature can be maintained at or above a predeterminedminimum regardless of most ambient conditions.

SUMMARY OF THE INVENTION The present invention is particularly directedto at least one damper box which overlies the condenser housing and isfluid coupled to the hot air discharge opening within the condenserhousing. The damper box has a portion which extends forwardly beyond thefront of the condenser housing and overhangs the same. A first dischargeopening in the top of the box permits complete discharge of the heatedcondenser air in normal fashion. A set of louvers are positioned withinthe box intermediate of top and bottom aligned horizontal openings. Asecond bottom opening, in the overhang portion, controls recirculationof a portion of the heated air from the discharge side of the condenserto the intake side of the condenser.

A damper motor may be fixed to the damper box for rotating the louversin unison between a horizontal position tending to recirculate thecondenser discharge air or a generally vertical position in which theheated condenser discharge air passes directly through the top of thedamper box. A thermostat mounted exterior of the auxiliary housing isoperatively coupled to the damper motor for controlling the position ofthe louvers. Linkage connecting the damper motor to the louvers includesadjusting means permitting the percentage of recirculated air to bevaried. For a large condenser unit having multiple condenser coils inside-byside fashion, a plurality of damper boxes may be provided intandem operated from a single damper motor with shafts extending betweenaligned louvers of respective boxes and wherein one louver set acts as amaster unit and the second acts as a slave unit.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of atandem damper box arrangement used in conjunction with an outdoorcondenser and forming a preferred embodiment of the present invention.

FIG. 2 is an end elevational view of the arrangement illustrated in FIG.1.

FIG. 3 is a sectional view of the master damper box of FIG. 1 takenabout line 3-3. Y 1

DESCRIPTION OF THE PREFERRED EMBODIMENT The motorized damper box of thepresent invention has application to space conditioning systems for refrigeration and air conditioning use, in which the condenser coils arehoused in position for normal exposure 'to the outside air. Referring tothe drawings, the condenser to which the invention has application, isconstituted by a rectangular housing or casing 10 comprising verticalsidewalls l2 and a front wall 14 and having a top or cover 16 providedwith one or more elongated rectangular openings such as opening 18, FIG.3, which is positioned to the rear of the condenser coil 20. In thisrespect, as indicated in FIG. 3, the front wall 14 is provided with atleast one large rectangular opening 22, and immediately behind thisopening and within an area defined by the front wall 14 and a flange 24is located in vertical orientation, the condenser coil 20, through whichthe air for cooling of the coil passes, as indicated by arrows 26. Thecoil 20 is cooled by forced air under operation of a blower (not shown)which lies internally of the condenser housing 10 and downstream ofcondenser coil 20. The opening 18 in addition to being formed by theflange 24, is further defined by a vertical partition 28 which causesalong with convection currents, the heated condenser air to rise andpass through discharge opening 18 within cover 16. Normally, the opening18 within the top or cover 16 of the condenser housing or casing 10 isprovided with a grill (not shown) inserted within the same andpermitting air to pass through openings within the grill virtuallyunimpeded. I

The present invention is directed specifically to the employment of oneor more motorized damper boxes which may be fixedly mounted on top ofthe condenser housing, overlying the condenser air discharge opening andincorporating means for recirculating the heated condenser air to theintake opening at the front of the condenser housing for raising theambient available to the condenser. In this respect, as illustrated inFIG. 1, there is provided in tandem, a first, master damper box 30fixedly mounted to the cover or top 16 of condenser housing and havingmechanically coupled thereto a second slave damper box 32 of generallyidentical construction with both damper boxes being operated by a singledamper drive motor 34 fixed to the rear of damper box 30. Like elementswith both boxes are given the same numerical designations. Essentially,each damper box comprises a rectangular housing defined by pairedsidewalls 34 and 36 connected together by a front wall 38 and a rearwall 40 with the bottom of a damper box being essentially open and withthe top being provided with a short cover section or top 41 at the frontthereof and extending rearwardly at least to the extent of the overhangof the damper box relative to the front wall 14 of the condenser housing10. Each damper box, therefore, is provided with a discharge opening 42within the top rear half of the damper box and a vertically aligned rearbottom opening 44, which overlies the discharge opening 18 of thecondenser housing 10. A front bottom opening 45 of boxes 30 and 32 alsooverlies the air intake area immediately in front of the intake opening22 of the condenser housing 10. The rear wall 40 of each damper box isprovided with a right angle flange 46 permitting the damper box to befixedly attached to the cover 16 of the condenser housing 10 in alongitudinal direction along the rear edge of condenser dischargeopening 18 through the use of rivets, screws, bolts, etc. (not shown).Further, extending between the sidewalls 34 and 36 is a depending, L-shaped mounting bar 48 with its vertical portion conforming to a flange24 defining the front edge of the same condenser air discharge opening18. Bar 48 is fixedly coupled to the cover 16 adjacent the front edge ofopening 18 by similar coupling means such as bolts,

screws or the like. The bar 48 acts in conjunction with partition 50which extends downwardly from the inner end of cover 41, and which maybe welded or otherwise attached thereto, to define a relatively narrowhorizontal air passage 52 which permits the selective flow of at least aportion of the heated condenser air into a chamber 54 defined by thefront wall 38, cover 41 and the partition 50 of each damper box 30 and32. The deflected, heated air escapes from chamber 54 in a downwarddirection through opening 45 in the bottom of the damper box whichoverlies the intake area of the condenser, specifically mixing with theincoming ambient air and raising the temperature of the same prior topassing through condenser coil 20.

The selective recirculation of the heated condenser air is achievedthrough the use of a plurality of pivotal damper blades or louvers 56formed of stamped sheet metal or the like and mounted for pivoting aboutindividual horizontally aligned pivot axes, which are also in line withthe bottom end of vertical partition 50, each axis defined by respectivemounting shafts 58 at both ends of the blades. Aligned openings areprovided within the sidewalls 34 and 36 with the shafts 58 protrudingtherethrough and being fixedly coupled to respective ends of the damperblades or louvers by straps 60. In this respect, each blade isconfigured such that the outer ends terminate in angularly bent edges62, while the center of each blade is grooved as at 64 permitting theshafts 58 to be partially received by the grooves 64 and held inposition by the straps 60 which are bent to form a central recess as at66. The shafts which are inserted through the holes of slightly greaterdiameter within sidewalls 34 and 36 of the damper box, project withinthe openings formed by the straps 60 and the grooved blades 56. Whilethe blades can be pivoted to fully closed position in which the bentedges 62 abut, they are normally held in a partially closed position todeflect a portion of the heated condenser air for recirculation as shownin FIG. 3. In the fully open position, practically all the condenser airpasses by convection and forced flow due to blower operation, verticallyupwards for discharge through the opening 42 within the top of eachdamper box.

In order to pivot the blades 56 in unison to effect recirculation asdesired, the ends of shafts 58 which protrude from the left handsidewall 34 of the damper box 30, for instance, are each provided with adamper crank arm 68, the inner end of each crank arm being coupled toits shaft by screw 70. Each damper crank arm 68 carries, at its outerend, a pin 72 projecting outwardly therefrom and generally parallel tothe louver mounting shafts 58, the pin 72 being bored and beingpositioned on the damper arm such that a common connecting rod 74 passestherethrough and acts to mechanically interlock all three damper crankarms 68 associated with louvers or blades 56 for both the master damperbox 30 and the slave damper box 32.

Further, one of the damper crank arms 68 in this case, the right handcrank arm, FIG. 2, is further provided with an elongated slot 76 whichslidably carries, adjustably positioned pin 78 forming a lockable pivotpoint for a damper arm drive rod 80 which acts as the link between thedrive motor crank arm 82 and the interlocked louvers or blades 56. Thedamper motor 34 constitutes a low power D. C. or A. C. drive motor whoseoutput or drive shaft 84 protrudes through a mounting bracket 86 whichfixes the motor 34 to the rear wall 40 of the master damper box 30. Thedrive shaft 84 carries a motor crank arm 82 which is quite similar inconfiguration and construction to right hand damper crank arm 68carrying the adjustment slot 76. The motor crank arm 82 carries a slot87 which supports a longitudinally adjustable and lockable pivot pin 88which receives one end of the connecting link or drive rod 80, the otherend of which is received by pivot pin 78 associated with the right handdamper crank arm 68. The damper drive motor 34 is powered fromelectrical source (not shown) under control of a thermostat 90 which inthis case is fixed to the rear wall 40 of the master damper box 30. Abracket 92 supports the thermostat bulb 94 in a position such that itmay readily sense the outside air temperature unaffected by the heatedair passing through the master damper box, and lead 96 passing throughthe rear wall 40 by means of bushing 98 permits control of an electricalcircuit which includes the thermostat bulb 94 and the damper drive motor34.

In the illustrated environment of use, the condenser housing 10 may, infact, comprise one portion of a combination heating-cooling unit ofwhich the refrigeration system components may occupy the right handportion of the condenser housing 10, as seen from the front, and inwhich case, theopenings 18 within the top or cover 16 of the condenserhousing extend longitudinally parallel to the front wall 14 justrearwardly of the condenser coil 20 and over a distance considerably inexcess of the width of the master damper box 30. In this case, a pair ofside-by-side condenser coils 20 are carried internally of housing and inorder to obtain the desired hot condenser air recirculation to theintake openings 22 within the front wall 14 of condenser housing 10 forboth condensers, it is necessary to provide a plurality of damper boxesin series, that is, in tandem. In this respect, the shafts 58 which arecarried by wall 36 of the master damper box extend well beyond theoutside of the damper box 30 and in fact pass through wall 34 of theslave damper box 32and are fixed in the identical manner, at theiropposite ends, to the louvers or damper blades 56 of the slave damperbox 32. In all other respects, the slave damper box 32 is identical inconstruction to that of the master damper box 30 with the exception thatthere is no drive motor or thermostat for controlling the slave damperbox 32 independently of the master damper box 30. Pivoting or shiftingthe position of all damper blades 56emanates from the single drive motor34 carried by the master damper box 30. Further, while the slave damperbox 32 is illustrated as being longitudinally spaced from the masterdamper box, in fact the two boxes may be placed essentially side-by-sidedepending only in the position of openings 18 within the-housing cover16, and thus maximum efficiency is achieved in recirculating a portionof the heated condensed air to the inlet side of the condenser formixing with the fresh outside air. Further, while the master damper box30 and the slave damper box 32 are illustrated as being spacedlongitudinally in FIG. 1, this is because in the illustratedapplication, for an eight ton refrigeration unit, there is positionedwithin housing 10' a pair of longitudinally aligned in-line condensercoils 20 with each condenser being provided with a fan or blower forforced movement of the air through the condenser and for dischargethrough respective longitudinally spaced openings, in this case, withinthe top or cover 16 of the condenser housing 10. Alternatively, thedamper box may comprise a single unit which extends longitudinallyacross both openings 18 within the larger ton units and in which case,the forward end of the damper box overlies air intake openings to bothcondenser coils.

During operation, and assuming that ambient conditions are such that theoutsideair temperature is in excess of 50 F., the louvers 56 for boththe master damper box 30 and the slave damper box 32 will be positionedas essentially shown in FIGS. 1 and 2, that is, in the fully openposition, whereby all of the condenser air escapes upwardly through theopenings 42 within the top of both damper boxes and without any heatedair being recirculated to the front of the condenser housing 10. Withthe control system controlling the damper drive motor 34set to operateat 50 F., when the temperature drops below 50 F a circuit is completedby the thermostat bulb 94, such that the damper drive motor 34 isenergized. This causes the damper blades or louvers 56 to move from thefully open position shown towards closed position as indicated in FIG.3, and the condenser discharge air emanating from the condenser housing10 through the top openings 18, is forcibly directed into chamber 54 andescapes through the front at bottom opening 45 within the bottom of eachdamper box for mixing with the cold outside air and raises the ambientby approximately 30 over the free ambient. This results in an increasein condensing pressure of approximately psi, and as a result therefrigeration unit incorporating the condenser coils 20 may operate downto 20 F.

Where the present invention has application to a combination heating andcooling unit in order to prevent the dampers from closing during theheating mode, an electrical interlock is provided by means of a relay(not shown) wired in parallel with the cooling relay (not shown).Further to permit cold starts a timer (not shown) is employed whichdelays operation of the damper motor 34 by approximately five minutes toallow the suction to build up to satisfactory levels.

From the above, it is readily apparent that one or more damper boxes asa complete subassembly may be readily incorporated or attached to thetop of an existing condenser housing by the simple expedient of removingthe condenser discharge grill overlying an opening such as the topopening 18 in condenser 10 and securing the damper to the top of thecondenser housing by means of screws or bolts and by using the sameholes as mounted the removed discharge grill. Where needed, a secondaryidentically constructed damper box may be employed as a slave damper, inwhich by the simple expedient of employing relatively long shafts as ameans for interconnecting respective blades or louvers of the slavedamper box 32 to the respective louvers within the master damper box 30,the drive motor of the master damper box drives both sets of louvers. Toprevent a continued build up in the condenser discharge air temperature,the dampers are so constructed that they do not fully close butpreferably move to a partially inclined position from the vertical asillustrated in FIG. 3 permitting a portion of the hot condenser air toescape while taking in a continuous supply of fresh air.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is: 1. In a condenser forming a component of arefrigerating system and normally being exposed to outside air andincluding a housing enclosing the condenser coil and having a first,vertical opening defining a condenser air intake facing the condensercoil, and a horizontal opening within the top of thehousing defining awarm air discharge opening downstream of said coil, the improvementcomprising:

at least one damper box supported on top of said condenser housing andhaving aligned intake and discharge openings overlying said condenserhousing warm air discharge opening,

said damper box further including a frontal portion overhanging thefront of said condenser housing and including a discharge opening withinthe bottom of the same beyond the front wall of said condenser housing,and

a horizontal array of selectively adjustable damper blades within saiddamper box positioned intermediate the aligned inlet and dischargeopenings of said damper box,

whereby, upon closure of said damper blades, at least a portion of saidhot condenser discharge air is deflected towards said frontal portion ofsaid damper box for discharge through the bottom opening within the sameand recirculation, with the incoming fresh air passing through saidcondenser housing intake opening.

2. The condenser as claimed in claim 1, wherein said damper boxcomprises a rectangular housing including imperforate side, front andrear walls, the bottom of said damper box being essentially open andsaid top of said box also being open at the rear but including a coveroverlying the frontal overhang portion to prevent discharge of thedeflected hot condenser discharge air except through that portion of theopening within the bottom of said box which extends beyond the frontwall of said condenser housing.

3. The condenser as claimed in claim 2, further comprising a verticalpartition extending across the damper box from one sidewall to the otherand downwardly from the inner edge of said cover and terminating shortof the bottom of said damper box, and wherein said plurality of damperblades are pivotably mounted on respective axes which are coplanar withthe bottom edge of said vertical partition.

4. The condenser as claimed in claim 3, wherein said blades are pivotedby shafts extending through said damper box sidewalls and fixed thereto,and wherein crank arms are fixed to the ends of said shafts androtatable therewith, means commonly connect said damper crank arms forrespective blades together for pivoting in unison, a damper drive motoris fixed to said damper box with a drive shaft extending outwardlytherefrom and generally parallel with said damper mounting pivot shafts,a motor crank arm is fixed to the said motor drive shaft, and adjustablelinkage interconnects said motor crank arm to one of said damper crankarms.

5. The condenser as claimed in claim 4, wherein at least one of saiddamper crank arms is provided with an elongated slot along a portion ofthe length thereof, said motor crank arm further comprising a similarelongated slot, lock-pivot means are carried by said slotsfor adjustablepositioning along the length of the same, and a connecting rodinterconnects said lock-pivot means for said damper crank arm and saidmotor crank arm, respectively.

6. The condenser as claimed in claim 5, wherein said condenser comprisestwo side-by-side condenser coils within said condenser housing andadjacent the front wall of the same, the top of said housing compriseshorizontal warm air discharge openings for respective coils, downstreamof the coils and rearwardly of the front wall of said condenser housing,said damper boxes comprise two in number constituting a longitudinalarray fixed to the top of said condenser housing, one of said damperboxes constituting a master damper box and carrying said damper drivemotor, said other damper box constituting a slave damper box, and meansfor mechanically intercoupling the damper blades of said master damperbox to those of said slave damper box for effecting blade rotation inunison under control of said master damper box drive motor.

7. The condenser as claimed in claim 6, wherein aligned openings areprovided within respective adjacent sidewalls of the master damper boxand the slave damper box, wherein said mechanical intercoupling meanscomprise damper blade mounting shafts extending through aligned openingswithin said respective sidewalls and means fixedly coupling respectiveends of said shafts to corresponding damper blades within said boxes.

1. In a condenser forming a component of a refrigerating system andnormally being exposed to outside air and including a housing enclosingthe condenser coil and having a first, vertical opening defining acondenser air intake facing the condenser coil, and a horizontal openingwithin the top of the housing defining a warm air discharge openingdownstream of said coil, the improvement comprising: at least one damperbox supported on top of said condenser housing and having aligned intakeand discharge openings overlying said condenser housing warm airdischarge opening, said damper box further including a frontal portionoverhanging the front of said condenser housing and including adischarge opening within the bottom of the same beyond the front wall ofsaid condenser housing, and a horizontal array of selectively adjustabledamper blades within said damper box positioned intermediate the alignedinlet and discharge openings of said damper box, whereby, upon closureof said damper blades, at least a portion of said hot condenserdischarge air is deflected towards said frontal portion of said damperbox for discharge through the bottom opening within the same andrecirculation, with the incoming fresh air passing through saidcondenser housing intake opening.
 2. The condenser as claimed in claim1, wherein said damper box comprises a rectangular housing includingimperforate side, front and rear walls, the bottom of said damper boxbeing essentially open and said top of said box also being open at therear but including a cover overlying the frontal overhang portion toprevent discharge of the deflected hot condenser discharge air exceptthrough that portion of the opening within the bottom of said box whichextends beyond the front wall of said condenser housing.
 3. Thecondenser as claimed in claim 2, further comprising a vertical partitionextending across the damper box from one sidewall to the other anddownwardly from the inner edge of said cover and terminating short ofthe bottom of said damper box, and wherein said plurality of damperblades are pivotably mounted on respective axes which are coplanar withthe bottom edge of said vertical partition.
 4. The condenser as claimedin claim 3, wherein said blades are pivoted by shafts extending throughsaid damper box sidewalls and fixed thereto, and wherein crank arms arefixed to the ends of said shafts and rotatable therewith, means commonlyconnect said damper crank arms for respective blades together forpivoting in unison, a damper drive motor is fixed to said damper boxwith a drive shaft extending outwardly therefrom and generally parallelwith said damper mounting pivot shafts, a motor crank arm is fixed tothe said motor drive shaft, and adjustable linkage interconnects saidmotor crank arm to one of said damper crank arms.
 5. The condenser asclaimed in claim 4, wherein at least one of said damper crank arms isprovided with an elongated slot along a portion of the length thereof,said motor crank arm further comprising a similar elongated slot,lock-pivot means are carried by said slots for adjustable positioningalong the length of the same, and a connecting rod interconnects saidlock-pivot means for said damper crank arm and said motor crank arm,respectively.
 6. The condenser as claimed in claim 5, wherein saidcondenser comprises two side-by-side condenser coils within saidcondenser housing and adjacent the front wall of the same, the top ofsaid housing comprises horizontal warm air discharge openings forrespective coils, downstream of the coils and rearwardly of the Frontwall of said condenser housing, said damper boxes comprise two in numberconstituting a longitudinal array fixed to the top of said condenserhousing, one of said damper boxes constituting a master damper box andcarrying said damper drive motor, said other damper box constituting aslave damper box, and means for mechanically intercoupling the damperblades of said master damper box to those of said slave damper box foreffecting blade rotation in unison under control of said master damperbox drive motor.
 7. The condenser as claimed in claim 6, wherein alignedopenings are provided within respective adjacent sidewalls of the masterdamper box and the slave damper box, wherein said mechanicalintercoupling means comprise damper blade mounting shafts extendingthrough aligned openings within said respective sidewalls and meansfixedly coupling respective ends of said shafts to corresponding damperblades within said boxes.